The catalytic converter 100 (FIG. 1) is used in a vehicle 102 to improve the quality of the exhaust gases 104 discharged from the engine 106 of the said vehicle.
To achieve this, the said catalytic converter 100 receives the gases 104 discharged by the engine 106 of the vehicle 102 in order to treat them by means, in particular, nitrogen oxide (NOx) traps or particle filters intended to remove the latter.
In certain cases, as is shown in FIG. 1, the said catalytic converter 100 may be located at the outlet of a turbocompressor T with which the said vehicle 102 is equipped if the vehicle is equipped with such a turbocompressor.
However, if such a turbocompressor is not present, the catalytic converter receives the exhaust gases of the engine directly.
Consequently, the exhaust gases 104 are sent to the exhaust pipe 108 of the vehicle 102, from which they can be emitted into the environment with a reduced pollutant level.
It is also known that the operation of a catalytic converter 100 depends on the internal temperature of the said catalytic converter, especially if the latter is used to treat the oxides of nitrogen (NOx).
The efficiency of a catalytic converter is therefore linked with the internal temperature of the catalytic converter and especially of the internal part of the said catalytic converter, which is also called a trap, which is used to interact with the pollutants and to remove them.
However, the determination of the temperature of this material is problematic given that it reaches elevated temperatures making the environment difficult for a probe.
In addition, the installation of a heat probe inside the catalytic converter is complicated and expensive.
The object of the present invention is to provide a process and a device that make it possible to determine the internal temperature of a catalytic converter, solving the above-mentioned problems. It results from the observation that the temperature of a catalytic converter is determined practically by two thermal phenomena, namely,                a thermal inertia to heating, i.e., the progressive heating of the catalytic converter, tending toward the temperature of the exhaust gases, due to the fact that the catalytic converter is a solid whose temperature rises under the effect of the exhaust gases passing through it, and        an exothermic reaction of the catalytic converter, i.e., the heating of the catalytic converter due to the release of energy produced by the oxidation reactions of particles in the catalytic converter.        
This is the case, in particular, when compounds such as carbon monoxides (CO) and hydrocarbons (HC) are oxidized in contact with the catalytic converter.